Ground to Ground (GTG) rockets such as the GRAD are a serious threat when hitting a civil populated territory.
The simple conventional GTG rocket structure has a clear inherent advantage of very simple launching means and a low-cost price tag, facilitating deployment of numerous launchers and utilization of numerous rockets which can be launched in large numbers and over a long period of time towards a desired territory, causing not only damage in property, injury and loss of life, but also substantial damage to the morale of the population which is subjected to prolonged and continuous threats.
Recently a new anti-rocket system called the “IRON DOME” system (provided by RAFAEL, Israel) has been introduced and used by the Israel Defense Forces (IDF) for protecting various towns that have been targeted by GRAD and other rockets, launched from the Gaza Strip.
A significant challenge in the interception of GTG rockets relates to the lethality problem: the vulnerable area of the rocket has relatively small dimensions and is surrounded by one or two layers of steel-made balls fitted onto the warhead explosive. Achievement of lethal interception is possible by using the hit-to-kill technique or by hitting of the threat's warhead by the very dense beam of relatively heavy fragments (e.g. known per se tungsten fragments of at least 35-40 grams).
Usage of hit-to-kill techniques for interception of spinning rockets appears to be problematic due to precession movement of the rocket with unpredictable amplitudes. On the other hand, the killing mechanism based on a fragmentation warhead requires a relatively large number of heavy fragments accelerated to required velocity to achieve the lethal effect. Dimensions and weight of the warhead directly influence the size, weight, and cost of the interception missile. The number of required lethal fragments generally depends on the volume of uncertainty regarding the position of the threat relative to the interception missile during the end game. The conventional approach for reducing this uncertainty volume is by using different on-board sensors such as for example RF seekers or electro-optical sensors. Another approach for reducing the uncertainty volume is disclosed in WO 2013/105093. This publication, by way of general background, discloses a counter-flying object system comprising a sensor array including at least one active sensor and at least two passive sensors configured to detect and track the flying object, and a missile launcher configured to launch an interceptor to intercept the flying object, wherein upon launching the interceptor, the sensor array is configured to determine the location of the interceptor and the flying object and send said object and interceptor locations to a control system, the control system being configured to provide mission data to the interceptor based on said object and interceptor locations for guiding the interceptor toward the flying object and activating a fragmentation warhead on or in the vicinity of the flying object when a lethality criteria is met.
Conventionally, such constraints compel utilization of a sophisticated and costly defense system, for defending against a comparatively simple and low-cost rocket launch system.
The contents of the above references are incorporated herein in their entirety.